Superconduction may be defined as the conduction of a current in a material without electrical resistance. Another definition of superconduction is the exhibition of the so-called Meissner effect wherein an external magnetic field is repelled by a material operating in a superconductive state.
The phenomenon of superconductivity was initially discovered by K. Onnes in 1911. The nearly resistance-free conduction of a current in liquid mercury, cooled with liquid helium, was observed. In 1933, Meissner discovered the magnetic phenomena, which bear his name, of superconductors.
In early 1986, J. G. Bednorz and K. A. Muller released their findings following several years of experimentation with oxide-containing superconductors of the perovskite-like and spinel-like structures. These materials, containing lanthanum, barium and copper oxide, exhibit superconductive properties at a temperature of about 30.degree. K. F. M. Mueller, Breakthroughs in Superconductivity, Journal of Metals, May 1987, Pages 6-8.
Dr. Paul Chu, also in early 1986, disclosed research indicating that the compound YBA.sub.2 CU.sub.3 Ox, where x is approximately 7, exhibits superconductive properties at temperatures which may be achieved by cooling with liquid nitrogen. Additional compounds have been disclosed which include rare earth elements mixed with cuprate oxides, and rare earth elements mixed with barium cuprate oxides. F. Fletcher, Developments in Superconductivity-High T.sub.c Oxides, Journal of Metals, May 1987, Pages 9-11.
The primary problem associated with the ceramic-metal superconductors is that they are not machinable, castable, or otherwise workable by conventional techniques. The ceramic-metals, when combined with certain elements, generally rare earth elements, form compounds which exhibit superconductive properties at about 87.degree. K. These compounds, which are generally referred to as cuprate oxides, are neither ductile, weldable, solderable, nor workable by conventional techniques. Further, the compounds tend to decompose when exposed to water or water vapor, and are highly oxidizing to other materials with which they come into contact.
Although it may be possible to form superconductive particles into a desired configuration, and then sinter the mass, sintering at a temperature sufficient to congeal the mass into a solid body seriously degrades or destroys the superconductive properties of the material.
In an attempt to form a cuprate oxide into a usable form, researchers at AT&T Bell Labs disclosed a flexible tape containing unfired Y-Ba-Cu-O superconducting oxide.
Numerous other reports of developments in superconductivity have appeared, for example, in High Technology, July, 1987, Business Week, Apr. 6, 1987, The Wall Street Journal, July 9, 1987, and the New York Times, July 3, 1987 and July 7, 1987. A common theme throughout these numerous publications has been the inability of the various researchers to work current, "high-temperature" superconductive materials into usable fixtures or structures. Although the materials have been formed into buttons and ribbons, no technique has been disclosed for forming these materials into a usable shape, for fastening the material to a conventional wire or electrical bus, or for manufacturing any useful object from the materials.